Sun failed to pull this one off when they attempted to turn StarOffice into a stick to beat MS. Yes, Google Docs have captured a lot of lightweight users. But it will be tough to persuade power MS Office users to switch, especially given the success of MS's switch to a subscription model.
Apple also made a run at Microsoft with Pages, Numbers and Keynote. Apple is known for intuitive user interfaces and they had some great looking templates that made it easy to create professional documents. The problem is still compatibility with Office. If you're not 100% compatible with the office file format, you aren't going to seen as a viable alternative.
I don't know. If you're part of an enterprise license, your goose is pretty much cooked...but for those small business and home users, I think that recurring monthly or yearly charge on the CC statement is going to make them a lot more willing to investigate alternatives.
